Dynamo-electric machine.



UNITED S ATES PATENT ome OEK 38161103 E ERA m rino 0on4. A. QB-A'EIQI or YORK- D namo-anaemic uacnmn.

To all whom it may concern Be it known that I, ERNST F. W. Anux- .ANDERSON, a citizen of the United States,

- By my invention I obtain a constant voltage generator for varying speeds and loads without the use of such regulators, that is, the regulation is inherent in my machine.-

My invention will best be understood by reference to the following description taken in connection with the accompanying drawing, in which Figure 1 shows a machine arranged in accordance with my invention and Fig. '2 is an ex lanatory diagram.

Re erring to Fig. 1, A represents the field magnet of a dynamo electric machine of the direct current type, having an armature B, the windings of which are connected to a commutator C. Mounted on the commutator C are two sets of commutator brushes b, b and b, b. The brushes 1), b are connected in a local circuit on a line displaced substantially 90 electrical degrees from the line of field magnetization. The second set of brushes 1), b are displaced substantially 90 electrical degrees from the first set and are connected to an external circuit D. The field magnet is provided with two field windings E and F, connected to produce opposing and unequal magneto-motive forces, one of which is arranged to produce a substantially constant flux, the other of which is arranged to produce avariable flux, wheres by-the voltage of the external circuit D is maintained substantially constant independently of the load, or the speed variations of the armature B.

Specification of Letters Patent. Application and m 1, 1911.

.tive for Patent d M r-v 31, 1.

seriaix 037,351, r

a short circuit current flowing through these brushes and the local circuit in which they are included. This short circuit current produces a secondary magnetization substantially at right angles to the line of field magnetization, and the rotation of the armature in the field produced by this secondary magnetization generates an electro-motive force between the brushes b, b, which electromotive force is impressed upon the external circuit. Therefore, the field which is effecbrushes b by the short circuit current between the brushes 6, b. In turn, this short circuit current depends upon that part of the magnetic field produced by the windings E and F which is cut by the armature conductors,

producing a voltage betweenthe b is the secondary fieldproduced The windings E and F are connected to produce opposing and unequal magneto-motive forces, the portion of the field magnet on which E, the stronger of the opposing field windings is wound, being saturated and the portion of the field magnet on which F, the otherofsaid opposing windings is wound, being unsaturated.

The field magnet structure comprises a yoke H and pole pieces I- and K. The field windings E are wound on restricted portions M of the pole pieces I, while the wind- 7 ings F are wound on the pole pieces K. The

pole pieces I have massive portions offering a path of low reluctance to the armature flux which produces the secondary field by reason of the long extending tips L, and connecting portions M betweenthe yoke and the pole tips. The pole pieces K are of large crosssect-ion and consequently unsaturated and of the opposite'polarity to that of the corresponding pole pieces I. I have shown the pole pieces K as extending between the yoke H and the pole tips L. The flux'produced in the field poles I is therefore substantially constant, while the flux produced in the field poles K varies with the voltage of the circuit D, in shunt with which the windings E and F are connected. Since the winding E is stronger than the'winding F, the fluxv of the pole pieces I is stronger than that of the pole pieces K, but, as the corresponding pole pieces are of opposite polarity, a por- The rotation of the armatureB in the field i tion of the flux of the pole pieces I, subproduced by the pole ieces of the field magstantially equal to that. ofthe pole pieces K, net A generates a di erence of potential bedoes notpass through the armature, but tween the brushes b, b, which results in finds a local path through the pole pieces K and the magnet frame. Consequently the flux, which is efiective for producing avoltage between the brushes 6, b, is the difference between the fluxes produced in the field poles I and K.

The voltage between the brushes 6, 7), pro-' since, this current is proportional to the voltage. Ordinates on the axis 0 represent the flux passing through the poles. The curve '0 is the curve of magnetization of the poles I, while the straight line curve 0 is the curve of magnetization of the poles K. Due to the-fact that the pole pieces I have a portion M of restricted cross-section, their curve of magnetization is substantially flat at that partof the curve at which the dynamo electric machine operates, but, since the pole pieces K are of large cross-section, their curve of magnetization is substantially a straight line having a constant slope to the axis U The machine operates approximately at the point of these curves intersected by the dotted line 56. At this point it will be noted that the magnetization of the saturated poles I is practically constant. Since a portion of the flux of the poles I, substantially equal to the flux of the poles K, passes through the poles K without passing through the armature, the

.voltage induced between the brushes 5, b

is proportional to the difference at this point between the ordinates of the curve (I and the straight line 0 that is, proportional to the small portion of the dotted line 5-6 which is included between these curves, If the voltage of the load circuit rises a very small amount for any cause, such as an increase of speed, a corresponding increase in the currents in the field coils E and'F is produced The effect is to shift the dotted line 5-6 a small amount toward the right. Even a very small shift of this line will greatly decrease the length of the portion of this line included between the curve 0 and the curve 0 so that the voltage between the exciting brushes Z), 6, and consequently the field produced by the short circuit current through these brushes, is very materially reduced, and the tendency to increase the voltage in the load circuit is offset by a reduction of the strength of the secondary field in which the armature rotates. voltage on the load circuit D produces a very great increase in the exciting voltage. In this way, very close regulation is obtained which is wholly independent of speed and of load variations.

Similarly a very slight decrease of The brushes 1), b are so placed that the armature current that flows through them tends to demagnetize the primary field and reduce its strength so that the voltage between the brushes does not remain constant. In order to compensate for this demagnetizing effect on the primary field,

or, in other words, for the armature reaction, I'employ a compensating winding G, so that the only field which is effective for producing a voltage between the brushes 6',

Z) is the secondary field produced by the short circuit current between the brushes 6, b.

Although I have shown and described two sets of commutator brushes, one of which is connected in a local circuit for producing a secondary magnetic field and by Letters Patent of the United States, is:

1. In a dynamo electric machine, a field magnet, an armature provided with a commutator, commutator brushes and connections forming for said brushes a local circuit for producing a secondary magnetic field and an external circuit, and means for producing in said field magnet in inductive relation to the armature coils connected to the brushes included in the local circuit effective flux which is the difference of two fluxes, one being a substantially constant flux and the other a flux proportional to the voltage between the brushes connected to the external circuit.

2.In a dynamo electric machine, a field magnet, an armature provided with a commutator, commutator brushes and connections forming for said brushes a local'circuit for producing a secondary n'zagnetic field and an external circuit, means for compensating for the armature reaction, and means for producing in said field magnet in inductive relation to the armature coils connected to the brushes included in the local circuit an effective flux which is the difi'erence of two fluxes, one being a substanitqially constant flux and the other a variable 3. In a dynamo electric machine, a field means for producing in said field magnet 11 in inductive relation to the armatureco l connected to the brushes included inithe' 1ocal-=.circuit an effective flux which is the difierence of two fluxes, one bemg a substantially constant flux and the other a flux proportional to the voltage between the brushes connected to the external circu t.

4. In a dynamo electric machine, a field a magnet, an armature provided with a commutator, commutator brushes andconnections forming for said brushes :1 local circuit for producing a secondary magnetic field and an external circuit, and two field 'windings connected to produce in said field cuit for producing a. secondary magnetic .field and an'external circuit, ai-windingfor compensating for the armature reaction,-and two field. windings connected to produce opposing and unequal magneto-motive forces,

one arranged to produce a substantially constant flux, and the other to produce a variable flux, whereby the voltage of said dynamo electric machine is constant.

6. In a dynamo electric machine, a

mutator, commutator brushes and connec tions forming for said brushes a local circuit for producing a secondary magnetic field and an external circuit,and two field windings connected to produce opposing and unequal magneto-motive forces, the portion of the field magnet on which the stronger of said opposing field windings is wound being saturated, and the portion of the field magnet on which the other of said opposing windings is wound beingunsaturated.

- 7. In a dynamo electric machine, a field magnet, an armature provided with a commutator, commutator brushes and connec-- tions forming for said brushes a local circuit for producing a secondary magnetic field and an external circuit, and two field windings connected to produce in said-field magnet in inductive relation to the armature coils connected to'the brushes included in the'local circuit opposing and unequal magneto motive forces, the portion of the field magnet on which the stronger of said opposing field windings is wound being satu-.

-ternal circuit.

maintained substantially field' magnet, an armature provided with a comtions forming for said brushes a local circuit for producing a secondary magnetic field mgs producing opposing and unequal magneto-motive forces, the portion of the field magnet on which the stronger of said Iopposing windings is wound being saturated, and the portion of the field magnet on which the other of said opposing wind' is wound being unsaturated, said field win ings being connected in shunt to said ex- 9. ha dynamo electric machine, a field magnet having a leakage path of low reluc;

ta es for the armature flux, an armature provided with a commutator, commutator brushes and. connections forming for said brushes a local circuit for producing a secondary magnetic field and an external circuit, and two field windings connected to produce opposing and unequal magnetomotive forces, the portion of the field magnet on which the stronger of said opposing field windings is wound being of restricted cross section so as to be saturated, and the portion of the field magnet on which the opposing windings is wound other of said being unsaturated;

10, In a dynamo electric-machine, a fieldmagnet having a leakage path of low reluc-' tance for the armature flux, an'armature provided with a commutator, commutator brushes and connections forming for said brushes a local circuit for producing a secondary magnetic field and an external cirand an external circuit, and two field windcuit, and two field windings producing opin in uctlve relatlonto send local c1rcu1t the portion of the field magnet on which the stronger of said opposingwindings is wound bemg of restricted cross section so as. to be saturated, and the portion of the field magnet on which the other of said op osin windings is wound being unsaturate sai field windings being connected in shunt to said external circuit.

11. In a dynamo electric machine, a field magnet structure, an armature provided with a commutator, commutator brushes and connections formin for said brushes a local circuit for pr ucing a secondary magnetic field and an external circuit, said and unequal magneto-motive forces field magnet structure comprising a yoke,

12. In a dynamo electric machine, a field magnet structure, an armature provided with a commutator, commutator brushes and connections forming for said brushes a local circuit for producing a secondary mag netic field and an external circuit, said field magnet structure comprising a yoke, pole pieces having massive portions offering a path of low reluctance to the armature flux and connecting portions of restricted cross section between said yoke and said massive portions, and other pole pieces, and two field windings producing opposing and unequal magneto-motive forces, the stronger of said opposing field windings being wound on said first mentioned pole pieces, and the other of said opposing windings being wound on said other pole pieces, said field windings being connected in shunt to said external circuit.

13. In adynamo electric machine, a field magnet structure, an armature provided with a commutator, commutator brushes and connections forming for said brushes :1 local circuit for producing a secondary magnetic field and an external circuit, said field magnet structure comprising a yoke, pole pieces having extending pole tips and connecting portions of restricted cross section between the yoke and pole tips, and other pole pieces of large cross section extendingbetween the yoke and said pole tips but separated from said pole tips by an air gap, and two field windings connected to produce opposing and unequal magneto-motive forces, the stronger of said opposing field windings being wound on said first mentioned pole pieces, and the other of said opposing windings being wound upon the other pole pieces.

14. In a dynamo electric machine, a field magnet structure, an armature provided with a commutator, commutator brushes and connections forming for said brushes a local circuit for producing a secondary magnetic field and an external circuit, said field magnet structure comprising a yoke, pole pieces having extending pole tips and connecting portions of restricted cross section between the yoke and the pole tips, and other pole pieces of large cross section extending between the yoke and said pole tips but separated from said pole tips by an air gap, and two field windings producing opposing and unequal magneto-motive forces, the stronger of said opposing field windings being wound on said first mentioned pole pieces, and the other of said opposing windings being wound upon the other pole pieces, said field windings being connected in shunt to said external circuit.

15. In a dynamo electric machine, a field magnet, an armature provided withv a commutator, commutator brushes and connections forming for said brushes a local circuit for producing a secondary magnetic field and an external circuit, a winding for compensating for' the armature reaction, and two field windings connected to produce opposing and unequal magneto-motive forces, the portion of the field magnet on which the stronger of said opposing field windings is wound being saturated, and the portion of the field magnet on which the other of said opposing windings is wound being unsaturated.

16. In a dynamo electric machine, a field magnet, an armature provided with a commutator, commutator brushes and connections forming for said brushes a local circuit for producing a secondary magnetic field and an external circuit, a winding connected in series with said external circuit for compensating for the armature reaction, and two field windings producing opposing and unequal magneto-motive forces, the portion of the field magnet on which the stronger of said opposing windings is wound being saturated, and the portion of the field magnet on which the other of said opposing windings is wound being unsaturated, said field windings being connected in shunt to said external circuit. 1 a

17. In a dynamo electric machine, a field magnet having a leakage path of low reluctance for the armature flux, an armature provided with a commutator, commutator brushes and connections forming for said brushes a local circuit for producing a secondary magnetic field and an external circuit, a winding for compensating for the armature reaction, and two field windings connected to produce opposing and unequal magneto-motive forces, the portion of the field magnet on which the stronger of said opposing field windings is wound being of restricted cross section so as to be saturated, and the portion of the field magnet on which the other of said opposing windings is wound beinv unsaturated.

18. In a dynamo electric machine, a field magnet having a leakage path of low reluctance for the armature flux, an armature provided with a commutator, commutator brushes and connections forming forsaid brushes a local circuit for producing a secondary magnetic field and an external circuit, a winding connected in series with said external circuit for compensating for the ar mature'reaction, and two field windings producing opposing and unequal magneto-motive forces in inductive relation to said local circuit, the portion of the field magnet on which the stronger of said opposing windings is wound being of restricted cross section so as to be saturated, and the portion of the field magnet on which the other of said opposing windings is wound being unsaturated, said field windings being connected in shunt to said external circuit.

19.. In a dynamo electric machine, a field magnet structure, an armature provided with a commutator, commutator brushes'and connections forming vfor said vbrushes a local circuit for producing a secondary magnetic' field and an external circuit, a winding for compensating for the armature reaction, said field magnet structure comprising a yoke, pole pieces having massive portions offering a path-of low reluctance to the armature flux and connecting portions of restricted cross section between the yoke and said massive portions, and other pole pieces, and two field windings connected to produce opposing and unequal magneto-motive forces, the stronger of said opposing field windings being wound on said first mentioned pole pieces, and the other of said opposing windings being wound on said other-Pole pieces.

20. In a dynamo electric machine, a field magnet structure, an armature provided with a commutator, commutator brushes and connections forming for said brushes a local circuit for producing a secondary magnetic field and an external circuit, a winding connected in series with said external circuit for compensating for the armature reaction, said field magnet structure comprising a yoke, pole pieces having massive portions offerin a path of low reluctance to the armature ux and connecting portions of restricted cross section between said yoke and said massive portions, and other pole pieces, and

two field windings producing opposing and unequal magneto-motive forces, the stronger of said opposing field windingsbeing wound on said first mentioned pole pieces, and the other of said opposing windings being wound on said other-pole pieces, said field windings being connected in shunt to said external circuit.

21. In a dynamo electric machine, a field magnet structure, an armature provided with a commutator, commutator brushes and connections forming for said brushes a local circuit for producing a secondary magnetic field and an external circuit, a winding for compensating for the armature reaction,

gap, and two field windings connected to produce opposing and unequal magneto-motive forces, the stronger of said opposing field windings being wound on said first mentionedpole pieces, and the other of said opposing windings being wound upon the other pole pieces.

22. In a dynamo electric machine, a field magnet structure, an armature provided with a commutator, commutator brushes and connections forming for said brushes a local circuit for producing a secondary magnetic field and an external circuit, a winding connected in series with said external circuit for compensating for the armature reaction, said field magnet structure comprising a yoke, pole pieces having extending pole tlps and connecting portions of restricted cross section between the yoke and the pole tips,

and other pole pieces of large cross section extending betweenthe yoke and said pole tips but separated from said pole tips by an air gap, and two field windings producing opposing and unequal magneto motive forces, the stronger of said opposing field windings being wound on said first mentioned pole pieces, and the other of said opposing windings being wound upon the other pole pieces, said field wlndlngs being connected in shunt to said external circuit.

In witness whereof, I have hereunto set my hand this 6th day of July, 1911.

ERNST F. W. ALEXANDERSON.

lVitnesses:

BENJAMIN B. HULL, MARGARET E. WOOLLEY. 

